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C. A. RANDALL. TELEPHONE SYSTEM AND APPARATUS.

No. 271,513. Patented Ja11.30,1883.

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CHARLES A. RANDALL, OF NEW YORK, N. Y.

TELEPHON SYSTEM AND APPARATUS.

' SPECIFICATION forming part of Letters Patent No. 271,513, datedJanuary 30, 1883.

Application filed September 11, 1882. (No model.)

To all whom it may concern:

Be it known that I, CHARLES A. RANDALL, al citizen ofthe United States,residing at New York city, in the county and State of New York, haveinvented new and useful Improvements in Telephone System and Apparatus,of which the following is a specification.

This invention relates to that class of telephone-exchange systems andapparatus in which the subscribers7 lilies radiate from a switchboard ata central oltice provided with nppararusi'or receiving and transmittingcalls. 'lhe objects ot' the invention are to facilitate the receipt andtransmittal of calls at and from the central ot'tice; to enable theswitch-board operator to know at all times what subscribers lines are inuse without cuttingin/7 and to effect automatically the cuttingin andont of circuit' the several apparatus at the subscribers7 offices, asrequired.

The invention consists in certain novel constructions and combinationsof devices for accomplishing these objects, as will be hereinafterdescribed, and pointed out in the claims..

In the drawings, Figure lv is ayiew in elevation ot' the apparatus atthe central ofce and a single connected subscribers station. Fig. 2 is adiametric section of the switchT board, in the line w at of Fig. 1. l

The letter A indicates the base or supporting board of the switch-board.lt is made of wood or other nonconducting material, and is provided onits front with a central metallic plate, D2, which by a wire, d, isconnected with a receiving-telephone, D3, which is connected with atransmitter, D4, which is in turn connected with the ground through abattery, B2.

f In a circle around the plate D2 are arranged a series of individuallyT-insulated metallic blocks, indicated by the numerals l 2 3 4, &c. Theseblocks are connected with the centraloftice terminals of thesubscribers7 lines, re spcctively, and each is provided with an attachedconnector, G, and a plu g-socket, s, each connector being provided witha plug, c, which tits all the sockets. Each connector C is made ot' ametallic spring strip or wire doubled in the form of a letter U and hasthe end of oneV leg in swiveling connection with its block, while theother legis slightly shorter and proi vided with a plug of such sizethat it will be held by friction in any of the switch-boardplug-sockets. The connector may be easily flexed, so that its plug mayform theconnections hereinafter described, and will resume its normalshape when the plug is released. The precise shape ot' the connector isnot material. It may have several bends or one or more coils formed init, it' desired, the main object being to have it of such resiliencethat it will stand out froml the board and resume its position when leftfree after use, so that it will not become entangled with otherconnectors.

Outside the circle ot' numbered blocks is arranged a metal ring, B,which is provided with a socket, s', behind each block, and said ring isconnected by a wire, b, with a call-operators receivingtelephone, B,which is connected with a transmitter, B2, in the usual manner, and thetransmitter is connected to ground.

Surrounding the ring B and insulated therefrom is another metallic ring,D, which is 00nnected with the central plate, D2, by a wire, d2,(indicated 'by a dotted line.)

The several .terminal blocks 1 2 3 4, dto., are respectively connectedwith the coils 0f magnets N 'N2 N3 N4, and so on, and these coils areconnected with the respective subscribers lines, the ollce of themagnets being to indicate to the switch-board operator when the lines towhich they are connected are in use, and thereby obviate the necessityof his connecting his telephone with any line in order to ascertain it'it be in use or if conversation has been discontinued over two lineswhich have been connected. If anyline isin use, the magnet connected inthat line will attract its armature, owing to its being then connectedin circuit with the subscribers battery, as will presently appear.

The letter w indicates a wire connecting the terminal block l of theswitch-board with one terminal of the coils of indicating-magnet N, theother termin al ot' said coils being connected with the subscriber-sline l/V, which leads to Subscribers Station No. l, which is so markedon thedrawings. At the subscribers station the line W divides at thepoint marked y, one branch, H, leading tothe receiver R, and connectedtherewith in a manner presently to be IOO . r3 are not connected.

described, while the other branch, H', leads to the transmitter T andconnects with one terminal ofthe secondary circuit of' itsinductioncoil, the other terminal connecting through a switch, h, withone pole of' the station-battery G, from the other pole of` which awire, g, leads to the receiver. From the wire g leads a branch wire, h',terminating in a contact-plate, h2,with which the switch his adapted tobe brought in contact for the purpose of cutting out the batterv.

The receiver R has attached to its case a laterally-projecting tube, t',ot' insulating maferial, within which are two pairs of metallic andpreferably elastic fingers, 1' r and r2 r3, the pair of fingers i* i"vprojecting toward the middle of the tube from one end, while the pair r2r3 project toward the middle from the opposite end. In the space betweenthe ends of the two pairs ot' fingers is a loose metallic ball, M, andwhen the tube B extends upward with respect to the case of' thereceiver, as shown in Fig. 1, the metallic ball M will rest upon andelectrically connect the lingers r2 and r3; but if' the tube B isreversed the ball will rest upon and connect the fingers rr. The branchH of the line-wire connects with the finger r2, and from the finger r3 awire, I, connects with one terminal ofthe coils of' the bell-magnet K,from the other terminal ot' which a wire, 1', leads to ground. Then thereceiver B and tube R are in the position shown in the drawings, whichis their normal position when hung up and not in use, it will beobserved that the line-wire YV is connected to ground through branch H,finger r2, ball M, ringer r3, wire I, bell-magnet coils, and wire 1', sothat the subscriber may receive a call through his bell when a currentis sent over his linewire. The wire g, which connects with the branchIl' through battery G and transmitter T, is connected with the finger r,while from the finger i" a wire, g, leads to one terminal of the coil ofthe receiver-magnet,.(not shown,) and from the other terminal of saidcoil a wire, g2, connects with wire I', and through it to ground. 1twill now be seen that if' the position of the receiver be reversed fromthat shown in the drawings, as before described, the ball M will connectthe lingers r and r', and theline W will be connected to ground throughbranch H', the transmitter T, battery G, wire g, finger i', ball M,finger o", wire g', receivercoil, wire g2, and a part of' wire 1', thestation apparatus being thus in condition for h'olding conversation withanother station or the central office. At the same time the bell-magnetwill be cut out of circuit, as the fingers r2 and At this time, also,the current from battery G traverses the line-wire and charges themagnet N at the central office, which, by its action upon its armature,gives notice to the switch-board operator that the line is in use.

At the central office the plugs c of' the connectors C are kept normallyin the sockets s',

behind their respective metal blocks 1 2 3 4, tc. When a subscriber-say,for instance, subscriber No. 1--wishes to communicate with anothersubscriber--say subscriber No. 4-he first puts his apparatus incondition for use, as just described, the circuitbeing completed fromhis battery over his line-wire W, coils of magnet N', terminal block 1at switch-board, its connecting end C, metallic ring B, and wire b, andthrough the call-operators instruments to ground. [le then informs thecall-operator with whom he wishes to communicate, and the calloperatorthereupon directs the switchboard operator to connect subscribers7lilies 1 and 4. The switch-board operator then first calls up subscriberNo. 4. This he does by removing theplug of the connector C of terminalblock 4 from its socket in ring B and placing said plug in contact withthe central plate, D, or ring I), thus connecting the subscribers lineNo. 4 with the ground through the connector C, plate Dz or ring D, wired, the switch-operators instruments, and battery B2. The current ofbattery B2 flows over the lineNo. 4 and rings the bell at thesubscribers station. When subscriber No. 4 receives the call he firstchanges his switch to contact with plate h2, places his receiver inposition for use, and replies through his transmitter that he is ready.The switch-board operator then connects the twolines by inserting theplug of connector() ot' block 4in the socket ofthe terminal block 1, anddisconnecting the plugof the connector of' block 1 from ring B, andallowing said connector to hang free 5 or the connection between the twoblocks could be made through the connector of block 1 and the connectorot' block 4 be lef't to hang free. The subscribers lines being thusconnected through their switch-board terminal blocks and the connectors,a current will traverse the connected lines from the battery ot'subscriber No. 1, as has been already fully explained,and theindicating-magnets N and N4 at the central office will show theswitch-board operator that these two lines are in use, and no otherconnection must be made therewith until the indicating-magnets show thatno current is traversing the lines and the conversation hasbeen'finished. The two lines are then to be reconnected with thecalloperators instrum ents through their terminal blocks 1 and 4,connectors C, ring B, and wire b. When a subscriber receives a call hisfirst step is to cut out his battery by changing the switch h to plateh2, iu order that it may not be in opposition to that of theswitch-board operator when the subscriber puts his receiver in positionfor use, or to that of' the calling subscriber when two lines areconnected. It is obvious, however, that the called subscriber might,instead of' cutting out, reverse his battery by means of' suitableswitch connections, so that it would work in correspondence with anotherbattery in circuit.

From the foregoing description it will be seen that the switch boardoperator may at loc IOS

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2711,5ll3 Y 3 any time call any subscriber with Whom the central oflicedesires to converse.

vThe magnets N, N2, N3, N, Src., may serve as annunciators by tittingthem with suitable drops; or vibrating armatures or pointers may beused.

I do not confine myself to the precise coustruction of apparatus shown,but reserve to myself the right to make such changes therein aslegitimately come within the scope and spirit ot' my invention. 1

l am aware that the terminals of subscribers lines at a central oce havebeen provided with attached flexible connections carrying' switch-plugs,and that switch-plates have been provided to receive said plugs formaking connections, and l do not claim such an arrangement.

l. A telephonie central-oice switch board provided with metallic lineterminal blocks or plates, each ot' which is provided with a permanentlyelectrically-connected connecting device provided with a switch-plug,and each of said blocks or plates being also provided with a plug-socketto receive the plugs of said connecting devices, respectively,substantially as described.

2. The switch-board having a metallic plate adapted for connection withbattery or ground, the circular series ot' metallic line terminalblocks, and the metallic ring B, adapted for connection with a call-operators instruments and for plug-connection with the line terminalblocks, respectively, substantially as described.

3. The combination, with the switch-board, of the circuit including thecalloperators instruments and ring B, the circuit including theswitch-board operator-s instruments and plate D2, and the line-circuits,including the metallic terminal blocks and connectors C, substantiallyas described.

4. The combination, with the subscribers lines and batteries and theswitch board terminals and intermediate connections, of theindicatingmagnets and devices at the subscribers office forautomatically connecting the station-batteries in circuit with saidindicating-magnets when the station apparatus is in use, and switches atthe stations for cutting the batteries out ot' the line, as required,substantially as described.

5. The combination, with the terminal blocks having plug-sockets, oftheoutwardlystanding loop-shaped flexible wire-connections C, each havingone leg swiveled in a terminal block and the other leg free and providedwith a plug to t the said plug-sockets, substantially as described.

In testimony whereot'l have hereunto set my hand in the presence ot' twosubscribing Witnesses.

CHARLES ADAMS RANDALL.

Vitnesses: y

J oHN BAssE'TT, J r., U. S. CARTER.

